JavaScript vs TypeScript

July 13, 2025

Hi, I’m Jack — a web developer with over 5 years of experience turning ideas into clean, functional websites. In this post, I want to break down one of the most common debates in modern web development: JavaScript vs TypeScript.

Why the Debate?

JavaScript has been the standard programming language of the web for decades. But as web apps have become more complex, developers have looked for tools to help them write safer, more maintainable code. One of the most popular solutions is TypeScript, a language that builds on JavaScript by adding static types.

Both have their place. Let’s compare them.

What is JavaScript?

JavaScript is a versatile, interpreted programming language supported by all browsers and central to web development. Its main features include:

  • Dynamic typing — variables can hold any type of value.
  • Prototype-based object orientation — enables flexible code structures.
  • Wide compatibility — runs everywhere, from browsers to servers.

Pros:

  • Simple to learn and start with.
  • Massive ecosystem.
  • No build steps needed—runs natively in browsers.

Cons:

  • No type safety—bugs can go undetected until runtime.
  • Can become hard to maintain as projects grow.

What is TypeScript?

TypeScript is a superset of JavaScript created by Microsoft. Every valid JS file is valid TS, but TypeScript adds:

  • Optional static typing — lets you define what type each variable or function parameter should be.
  • Advanced tooling — better code completion, refactoring, and error detection.
  • Custom types and interfaces — for more structured code.

Pros:

  • Catches bugs at compile time — safer code, especially in big projects.
  • Scales better for teams and large codebases.
  • Recommends better design patterns via types and interfaces.

Cons:

  • Requires a build step (you must compile TS to JS).
  • Slightly steeper learning curve.
  • Some third-party libraries may need type definitions.

Side-by-Side Example

Here’s a simple function in both languages:

JavaScript

function greet(name) {
  return "Hello, " + name.toUpperCase();
}

console.log(greet(42)); // Runtime error: name.toUpperCase is not a function

TypeScript

function greet(name: string): string {
  return "Hello, " + name.toUpperCase();
}

console.log(greet(42)); // Compile-time error: Argument of type 'number' is not assignable to parameter of type 'string'

TypeScript catches errors before you even run your app.

When to Use Each

| | JavaScript | TypeScript | |------------|---------------------------------------------|----------------------------------| | Project Size | Small/Medium | Medium/Large | | Prototyping | Fast, minimal setup | Extra step, but possible | | Learning Curve | Lower | Slightly higher (types, setup) | | Stability & Maintenance | Less structure | Safer, more maintainable | | Tooling | Good (with modern editors) | Excellent (intellisense, checks) |

My Experience

I started out writing pure JavaScript, and still reach for it on quick prototypes, WordPress tweaks, or when hacking together small scripts. But nearly every new project destined to “grow up” gets a TypeScript setup from day one. The ability to refactor with confidence and catch silly errors before launch is a game changer.

Conclusion

  • Choose JavaScript for rapid prototyping, beginner projects, or when working in environments where an extra build step is a hassle.
  • Choose TypeScript when code quality, maintainability, and scalability matter—or when collaborating with larger dev teams.

The best part? You don’t always have to decide upfront. TypeScript lets you migrate gradually and use as much or as little static typing as you need, even inside a mostly-JavaScript codebase.

Which do you prefer, and why? I’d love to hear your thoughts or experiences below!

Further Reading:

Let’s build something meaningful.